Arch Linux

Loustak

Member

Registered: 2020-01-16

Posts: 6

Screen backlight goes to 100% each time battery is plugged

Hello,

I have a Thinkpad T480. My graphic card is an intel one. And i'm using the xf86-video-intel package.
My problem is when I plug my battery the backlight brightness goes to 100% every time. I would like it not to change.

Any ideas?
Thanks

sabroad

Member

Registered: 2015-05-24

Posts: 242

Re: Screen backlight goes to 100% each time battery is plugged

when I plug my battery the backlight brightness goes to 100%

You don't mention which desktop environment you're using, so I'll take a stab in the dark and guess you need to set Gnome power management preferences.

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saint_abroad

Loustak

Member

Registered: 2020-01-16

Posts: 6

Re: Screen backlight goes to 100% each time battery is plugged

Yep sorry, I'm not using a desktop environment, only a window manager: dwm and that's all.

sabroad

Member

Registered: 2015-05-24

Posts: 242

Re: Screen backlight goes to 100% each time battery is plugged

dwm and that's all.

Do you use Laptop Mode Tools?

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saint_abroad

Loustak

Member

Registered: 2020-01-16

Posts: 6

Re: Screen backlight goes to 100% each time battery is plugged

I did check with pacman -Qi laptop-mode-tools it returned : error: package 'laptop-mode-tools' was not found.
So I'm not using it I think.

I have powertop installed trough. I don't know if it may cause this kind of behaviour?

Head_on_a_Stick

Member

From: London

Registered: 2014-02-20

Posts: 7,732

Website

Re: Screen backlight goes to 100% each time battery is plugged

Are you running a power manager at all? You should probably post your ~/.xinitrc

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Loustak

Member

Registered: 2020-01-16

Posts: 6

Re: Screen backlight goes to 100% each time battery is plugged

My xinitrc consits of a simple 'exec dwm'. I tried to use powertop, wich is if I remember correctly the only power manager I used.

sabroad

Member

Registered: 2015-05-24

Posts: 242

Re: Screen backlight goes to 100% each time battery is plugged

backlight brightness goes to 100%

What are you using to control this? What is 100%? Please post full output of any command involved.

Some thinkpads have brightness control in the BIOS.

Last edited by sabroad (2020-01-22 12:15:23)

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saint_abroad

Head_on_a_Stick

Member

From: London

Registered: 2014-02-20

Posts: 7,732

Website

Re: Screen backlight goes to 100% each time battery is plugged

My xinitrc consits of a simple 'exec dwm'.

The ArchWiki advises to copy the sample initrc from /etc/X11/xinit/ so that the various scripts under /etc/X11/xinit/xinitrc.d/ are run but this isn't as critical as some regular forum users seem to think. Nevertheless you should probably check those scripts to see if you need them, one of them is to ensure a working dbus session and that might be a factor here (but probably not).

Have you checked the systemd journal for any clues?

You could try running

udevadm monitor

then plug the power cable in and see if udev is doing anything.

I tried to use powertop, wich is if I remember correctly the only power manager I used.

I meant programs like xfce4-power-manager, which can control the backlight automatically.

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Are you infected with Wetiko?

Loustak

Member

Registered: 2020-01-16

Posts: 6

Re: Screen backlight goes to 100% each time battery is plugged

My xinitrc consits of a simple 'exec dwm'.

The ArchWiki advises to copy the sample initrc from /etc/X11/xinit/ so that the various scripts under /etc/X11/xinit/xinitrc.d/ are run but this isn't as critical as some regular forum users seem to think. Nevertheless you should probably check those scripts to see if you need them, one of them is to ensure a working dbus session and that might be a factor here (but probably not).

Have you checked the systemd journal for any clues?

You could try running

udevadm monitor

then plug the power cable in and see if udev is doing anything.

I tried to use powertop, wich is if I remember correctly the only power manager I used.

I meant programs like xfce4-power-manager, which can control the backlight automatically.

I set my brigthness low (something like 5%) then plugged in my power cable, the brightness then get back to 100%. I got the following output:

KERNEL[160.717686] change   /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:19/PNP0C09:00/PNP0C0A:00/power_supply/BAT0 (power_supply)
KERNEL[160.767446] change   /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:19/PNP0C09:00/PNP0C0A:00/power_supply/BAT0 (power_supply)
KERNEL[160.891265] change   /devices/platform/USBC000:00/typec/port0 (typec)
KERNEL[160.891297] add      /devices/platform/USBC000:00/typec/port0/port0-partner (typec)
UDEV  [160.896587] change   /devices/platform/USBC000:00/typec/port0 (typec)
UDEV  [160.899406] add      /devices/platform/USBC000:00/typec/port0/port0-partner (typec)
KERNEL[161.230328] change   /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:19/PNP0C09:00/ACPI0003:00/power_supply/AC (power_supply)
UDEV  [161.292181] change   /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:19/PNP0C09:00/ACPI0003:00/power_supply/AC (power_supply)
UDEV  [161.855500] change   /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:19/PNP0C09:00/PNP0C0A:00/power_supply/BAT0 (power_supply)
UDEV  [161.900845] change   /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:19/PNP0C09:00/PNP0C0A:00/power_supply/BAT0 (power_supply)

Last edited by Loustak (2020-01-24 10:18:12)

Head_on_a_Stick

Member

From: London

Registered: 2014-02-20

Posts: 7,732

Website

Re: Screen backlight goes to 100% each time battery is plugged

Perhaps it's a firmware "feature", have you checked the menus for anything relevant?

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Loustak

Member

Registered: 2020-01-16

Posts: 6

Re: Screen backlight goes to 100% each time battery is plugged

I'm not sure about wich menus you are talking about, do you means bios menu? i'll check that.